Make a loop of wire, twist it however you like, immerse it in soap solution, and lift it out. The resulting soap bubble will form a special surface, called a minimal surface, with boundary the wire loop.
Geometric Analysis, part of pure mathematics, predicts the shape of these surfaces. Minimal surfaces minimise area, and hence the energy embodied in a surface. They occur throughout nature: as the shapes of cell membranes, on an atomic scale as the shapes of certain catalysts, and as the apparent horizon around a black hole.
Their beauty also leads to their use in architecture, such as in the Water Cube (水立方) at the 2008 Olympics in Beijing. For example:
